Heavy towing seems like it could be abused and used against your opponent in the right circumstances. Damaged with a face-up disrupt move into your opponents' hex, tow them into an adjacent hex with your infantry, and have your infantry close assault them, in that order, maybe reword to only affect your allies' vehicles. Plus it seems like a lot to perform in a small amount of time, roughly 1 minute per turn.
Tank repair maybe once per game or maybe they have a set amount they can try to repair during a game.
Many moons ago Sharpe had a smoke special ability that we used a few times in a couple of games.
SMOKE: As only action in Movement Phase, the unit may roll AI dice. With 3 successes, place a Smoke in hex in range and LOS from the unit.
Sounds interesting. I assume by AI you mean Attack Infantry dice. So if I have 4 dice at long range I need 3 successes out of 4. Whereas at close range I might have 8 dice and have a better chance of succeeding to get the 3 successful rolls.
Correct plus can be used all game but need to decide if you would rather move or deploy smoke during the movement phase